de Almeida Marcelo Nunes, Corzo Cesar A, Zimmerman Jeffrey J, Linhares Daniel Correia Lima
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1811 Veterinary Medicine Annex, 1856 Christensen Dr. Ames, Ames, Iowa, 50011, USA.
Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
Porcine Health Manag. 2021 Apr 12;7(1):31. doi: 10.1186/s40813-021-00210-5.
Processing fluids (PF) and family oral fluids (FOF) are population-based surveillance samples collected from 2- to 5-day-old piglets and due-to-wean piglets, respectively. Although they are described for the surveillance of PRRSV in sows and piglet populations at processing and weaning, there is limited information on their use in commercial herds. This observational study described PRRSV RNA detection over time in PF, FOF, and piglet serum collected from farrowing groups in commercial breeding farms with the objective of achieving robust, practical, and effective PRRSV surveillance protocols. Weekly PF (an aggregate sample of all litters processed in a week from each room), and FOF (a convenience sample attempted from at least 20 individual litters in at least one farrowing room each week) samples were collected from six PRRSV-endemic commercial breeding herds for up to 38 weeks. A total of 561 PF room samples, 2400 individual litter FOF samples, and 600 serum samples (120 pools of 5 samples) were collected during the study period and tested for PRRSV RNA. Data were evaluated for patterns of PRRSV RNA detection by specimen within farms over time.
In particular, the detection of PRRSV was commonly sporadic over time within farms (weeks of PRRSV RNA negative results followed by one or more weeks of positive results); was often non-uniform within farms (negative and positive farrowing rooms at a given point in time); and PF and FOF testing results agreement was 75 and 80% at week and room level, respectively, demonstrating that both sampling methods could complement each other. Non-uniformity in PRRSV detection in rooms sampled within the same week and detection after ≥11 consecutive weeks of PRRSV negative PF and FOF results underline the challenge of consistently detecting the virus.
These results suggest that monitoring protocols for breeding herds attempting PRRSV control or elimination can use both PF and FOF to improve PRRSV detection in suckling pig populations.
加工液（PF）和仔猪口腔液（FOF）分别是从2至5日龄仔猪和即将断奶仔猪中采集的基于群体的监测样本。尽管它们被用于监测母猪和仔猪群体在加工和断奶时的猪繁殖与呼吸综合征病毒（PRRSV），但关于它们在商业猪群中的使用信息有限。这项观察性研究描述了从商业种猪场的产仔组中随时间推移在PF、FOF和仔猪血清中PRRSV RNA的检测情况，目的是制定稳健、实用且有效的PRRSV监测方案。每周从六个PRRSV流行的商业种猪场收集PF（每周从每个房间处理的所有窝仔猪的混合样本）和FOF（每周至少从一个产仔房间的至少20个个体窝仔猪中采集的便利样本）样本，持续38周。在研究期间共收集了561个PF房间样本、2400个个体窝FOF样本和600个血清样本（120组，每组5个样本），并检测PRRSV RNA。评估了农场内随时间推移按样本类型的PRRSV RNA检测模式。
特别是，PRRSV的检测在农场内随时间通常是零星的（PRRSV RNA阴性结果的周数后接着是一周或多周的阳性结果）；在农场内往往不均匀（在给定时间点有阴性和阳性产仔房间）；PF和FOF检测结果在周和房间水平的一致性分别为75%和80%，表明两种采样方法可以相互补充。同一周内采样房间中PRRSV检测的不均匀性以及PF和FOF连续≥11周PRRSV阴性结果后的检测突出了持续检测该病毒的挑战。
这些结果表明，试图控制或根除PRRSV的种猪场监测方案可以同时使用PF和FOF来提高哺乳仔猪群体中PRRSV的检测率。
